Changes to Medicare beneficiary identifier

10.1.1 - Changes to Medicare beneficiary identifier (Rev. 4247, Issued: 03-01-19, Effective: 04-01-19, Implementation: 04-01 -19) The term Medicare beneficiary identifier (Mbi) is a general term describing a beneficiary's Medicare identification number. For purposes of this manual, Medicare beneficiary identifier references both the Health Insurance Claim Number (HICN) and the Medicare Beneficiary Identifier (MBI) during the new Medicare card transition period and after for certain business areas that will continue to use the HICN as part of their processes. Changes in an individual’s entitlement to Medicare benefits may result in an individual being assigned a completely different HICN. For example, an individual not entitled to monthly benefits (000-00-0000T) marries and becomes entitled to wife’s benefits on her husband’s account (111-11-1111B). If a claim is submitted under the old HICN, the Common Working File (CWF) disposition code 51 will notify the A/B MAC (A), (B), (HHH), or DME MAC (whom we will refer to as the MAC when all are meant) of the new HICN. The MAC will annotate its records and use the new HICN when submitting future bills or claims.